Basic sound identification systems are known but there is a need for improved techniques. Background prior art can be found in: US2006/227237; WO99/56214; WO2008/016360; U.S. Pat. No. 5,276,629; Goldmann, R (2006), “Extracting High level semantics by means of speech audio and image primitives in surveillance”; Gonzalez, L (2006), “Enhancing video surveillance with audio events”; and Mitchell, C. J (2007), “Aligning Music Genre Taxonomies”, PhD Thesis, Anglia Ruskin University.
For further use merely in understanding the present invention, the following disclosures are referred to:                International patent application PCT/GB2008/001679, Data Processing Apparatus, published 20 Nov. 2008, Ipsotek Ltd.;        WO2006/075352 A, Valentino Franco et al., Surveillance method and surveillance device operating with said method, published 20 Jul. 2006;        US patent application US2006/22737 A, IBM;        International patent application WO2008/016360 A, IBM;        US patent application US2003/088411 A1, Motorola Inc.; and        US patent application US2002/135485, Arakawi Kaoru.        